For administration of drugs, medical adhesive sheet type preparations, so-called percutaneously absorptive preparations, have been drawing attention in recent years, in view of the feasibility of medication, easiness of controlling medication and the like, wherein the preparation is applied to the skin by the action of an adhesive.
Inherently, however, the skin functions as a barrier system to protect body against the outer environment and powerfully blocks the body from the invasion of foreign substances. For a pharmacological effect of a drug for percutaneous administration to be fully exerted, a percutaneously absorptive preparation having skin permeability overriding such barrier function needs to be developed.
In an attempt to improve skin permeability, a percutaneous absorption promoter is frequently added to an adhesive; iontophoresis is utilized wherein an ionized drug is percutaneously absorbed by conducting the skin; a drug is physically absorbed percutaneously by phonophoresis using ultrasonication; and the like.
On the other hand, many compounds have been reported to cause irritation to the skin when applied to percutaneous absorption. Because percutaneously absorptive preparations aim at percutaneous absorption of a drug into the body, percutaneous absorption of a drug, that may cause irritation to the skin, requires sufficient percutaneous absorption of the drug by the body at a concentration of the level free of irritation to the skin, which means the preparation should have conflicting actions.